Improving the Deliverability of Your Professional Emails
The deliverability of business emails depends on three combined factors: correct technical configuration of the domain (SPF, DKIM, DMARC), a clean sending reputation (few complaints, few bounces), and content that doesn't trigger mailbox providers' anti-spam filters. None of these three factors is enough on its own to guarantee that emails land in the inbox rather than in spam.
The real problem: a sent email isn't a received email
An email that's technically "sent successfully" on the sender's side can very well never reach the recipient's inbox, silently filtered into the spam folder or blocked before it even arrives. This mechanism is invisible to the sender: no alert indicates that a message was filtered, which makes the problem hard to detect without dedicated monitoring. A company can lose important business exchanges (quotes, invoices, follow-ups) for weeks without ever noticing.
Mailbox providers (notably Gmail, Outlook and Yahoo) have tightened their filtering criteria in recent years, particularly for domains sending significant volumes without proper technical authentication. A poorly configured domain starts at a trust disadvantage before the very first send.
The three pillars of technical authentication
- SPF (Sender Policy Framework): a DNS record listing the servers authorized to send emails on behalf of the domain. Without SPF, a receiving server can't verify that the email genuinely comes from a legitimate source, which increases its likelihood of being filtered.
- DKIM (DomainKeys Identified Mail): a cryptographic signature added to each email, letting the receiving server verify that the message wasn't altered in transit and genuinely comes from the domain it claims to.
- DMARC (Domain-based Message Authentication, Reporting and Conformance): a policy telling receiving servers what to do with emails that fail SPF or DKIM checks (accept, quarantine, or reject them), and providing reports on attempts to spoof the domain.
These three elements complement one another: SPF and DKIM authenticate the sender, while DMARC defines the policy applied on failure and provides visibility into potential abuse of the domain.
How to check and fix your configuration
- Check that SPF, DKIM and DMARC records exist using an online DNS diagnostic tool, by looking up the domain in question.
- Fix SPF if several services send emails on behalf of the domain (hosting provider, marketing tool, CRM) without all being listed, a frequent cause of authentication failure.
- Enable DKIM with each sending provider you use, as the configuration is generally specific to each service and must be done separately.
- Start DMARC in monitoring mode (
p=none), which collects reports without blocking any emails, before gradually moving to a stricter policy (quarantinethenreject) once the configuration is validated. - Test actual sending to several mailbox providers (Gmail, Outlook) and check that messages land in the inbox rather than in spam.
Domain reputation: a factor built over time
Beyond technical configuration, mailbox providers continuously assess the reputation of the domain and sending address, based on several signals:
- The complaint rate (emails marked as spam by recipients).
- The bounce rate (emails sent to invalid or non-existent addresses).
- Sending regularity, with a sudden spike in volume after a long period of inactivity read as a suspicious signal.
- Recipient engagement (opens, replies), which signals content perceived as relevant.
This reputation doesn't fix itself instantly: it improves gradually through regular, clean sending that's well received, typically over several weeks.
What quickly damages deliverability
- Buying or using an unqualified email address list, which generates a high bounce and complaint rate.
- Sending large volumes from a standard business address not designed for this purpose, instead of a dedicated email sending solution.
- Content that triggers standard anti-spam filters: excessive capitalization, aggressive sales language, links to unreliable domains.
- No clear unsubscribe link on marketing emails, both a legal requirement and a reputation factor.
- Changing sending infrastructure (new server, new tool) without a gradual warm-up period, a jarring signal for anti-spam filters.
What to remember
- Deliverability rests on three combined factors: technical authentication (SPF, DKIM, DMARC), sending reputation, and content quality.
- An email "sent successfully" on the sender's side isn't necessarily received in the inbox, and this filtering is invisible without dedicated monitoring.
- SPF must list every service authorized to send on behalf of the domain, a common oversight when several tools are in use.
- DMARC should be rolled out gradually, starting in monitoring mode before a strict policy.
- Domain reputation is built over time through regular, clean sending; it doesn't fix itself instantly.
Frequently asked questions
Why are my business emails landing in spam when they didn't before? This usually signals a reputation drop (complaints, high bounce rate) or a recent change in SPF/DKIM configuration. Switching sending providers or running a recent mass campaign is a common cause.
Are SPF, DKIM and DMARC enough to guarantee good deliverability? They're necessary but not sufficient. Deliverability also depends on domain reputation and the content of the emails.
How long does it take for a DNS change to improve deliverability? Technical propagation takes a few hours to 48 hours. The improvement in reputation is more gradual, often observed over several weeks.
Is sending a mass mailing from a standard business address a problem? Yes, generally. Infrastructure designed for one-to-one exchanges isn't suited to large volumes, which quickly damages reputation. Bulk sending calls for a dedicated solution.
In summary
Improving the deliverability of business emails means tackling technical authentication, sending reputation and content quality together, since none of the three is enough on its own. A correct SPF, DKIM and DMARC configuration is the essential starting point, to be backed up with clean sending practices over time. VeryAppi's subscription website plan includes technical configuration of professional emails from launch.
Frequently asked questions
›Why are my business emails landing in spam when they didn't before?
This usually signals a drop in the reputation of the sending domain or IP address: recipient complaints, a high bounce rate, or a recent change in technical configuration (SPF, DKIM). Switching sending providers or running a recent mass campaign is a common cause.
›Are SPF, DKIM and DMARC enough to guarantee good deliverability?
They're a necessary technical foundation, but not a sufficient one. Deliverability also depends on the reputation of the domain and sending IP, the content of the emails, and recipient behavior (opens, spam marking). A perfect technical setup won't stop content perceived as spam from being filtered.
›How long does it take for a DNS change to improve deliverability?
Technical propagation (SPF, DKIM, DMARC) usually takes a few hours to 48 hours. The improvement in reputation with mailbox providers is more gradual, typically observed over several weeks of regular, clean sending.
›Is sending a mass mailing from a standard business address a problem?
Yes, generally. An address and infrastructure designed for one-to-one exchanges (via Gmail, Outlook, or a standard hosting provider) aren't suited to sending large volumes, which quickly damages sender reputation. Bulk sending calls for a dedicated solution (a transactional or marketing email routing service).